- Ctrl-Tab and Ctrl-Shift-Tab to cycle tabs now loop around if reaching the end of the tab list

# Bugfixes and minor changes:

- Fix crash on showing/hiding of directory trees after closing a tab- Tabs no longer become unresponsive if not approving to close a busy tab- Directory comparison did not work properly on all but the first tab- Fix spurious error messages if connecting to a new site while synchronized browsing is enabled- *nix: Work around a bug in KDE preventing restore from minimize to notification area- Do not show update dialog if there is already some other dialog open- Fix synchronized browsing option on site-specific bookmarks